The development of the ventilatory control mechanism and the relationship between sleep and periodic respiration and apnea will be examined in the premature monkey, Macaca nemistrina, in order to elucidate the pathogenesis and pathophysiology of these phenomena. Simultaneous recording of respirations and electroencephalograms in premature animals of known postconceptual age in a standardized environment will examine the relationship between sleep stages and apnea and periodic brething. Tidal volumes, arterial gases, intrapleural pressures, and electroencephalograms will be recorded during introduction of increased F sub I CO2 and decreased F sub I O2 at various postnatal ages to ascertain the development of the ventilatory control mechanism in the premature primate. The same data will be collected during an increased F sub I CO2 stimulus during specific sleep stages to study possible changes in the CO2 response curve during sleep in this primate. The proposed investigation will provide baseline data on the development of the ventilatory control mechanism in primates and on the role of sleep in the etiology of apnea and periodic breathing. Results will serve as a stimulus to future research on the pathogenesis and treatment of two significant health problems: apnea in premature infants and the sudden infant death syndrome.